• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.571-576
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• 2002

Electromagnetic analysis has been made for the design of 3 MJ Compulsator (Compensated Pulsed Alternator, CPA) that will be used as the power supply system of the electrothermal-chemical launcher system. using finite element method with ANSYS/Emag. From the analysis results, it was possible to decide the excitation MMF and the rotor/stator size to obtain the desired output current. And using electromagnetic forces from the analysis results. the stresses on the components of 3 MJ CPA could be analyzed. The detailed design based on the analysis results has been made and the fabrication of 3 MJ CPA is in progress. Before assembling components into 3 MJ CPA. an experiment is being made to check the correspondence between analysis results and measurements.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.897-899
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• 2002

BLDCM(Brushless D.C. Motor) is widely used industrial application because of high efficiency and high power density. Especially, In servo system and home appliance, BLDCM is very useful due to high control performance and low acoustic noise. In this paper, 2.5HP rated BLDCM controller and drive was developed for tread mill application. The prototype BLDCM has 4 poles rotor and 24 slots stator. Ferrite was used as a rotor magnet due to the cost and temperature characteristic. For the stable operation of tread mill, over current and high temperature can be detected by the DSP control1er. For the commutation signal, switching patterns from the sensorless circuit and hall sensor signal are used in the DSP controller.

• Tribology and Lubricants
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• 제23권6호
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• pp.283-287
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• 2007

Permanent-magnet (PM) passive bearings use the repulsive forces between the rotor and the stator magnets for the bearing function. It is desirable that the stiffness of the bearing is maximized with the given volume of the magnet. The stiffness is affected by the magnet strength, the number of layers, and the magnetization patterns. Previously, finite-element method (FEM) has been used to maximize the stiffness of the bearing. In this paper, we used the equivalent current sheet method to calculate the stiffness. The validity of this approach is checked against FEM results. The optimized bearing is applied to a micro flywheel energy storage system.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2383-2388
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• 2011

LSMs are installed under girders along the long track. In order to improve the efficiency of the LSM, long stator LSM should be divided into the specified length and the propulsion inverters should have the system topology to generate high voltage and current for LSMs. This paper presents a system topology with two-step inverter in order to generate high voltage in inverter. A LSM propulsion system is developed and implemented in Maltab/Simulink. A system model of the two-step Inverter is applied to developed model. This paper demonstrates through simulation, advantages of multi-step inverter. The conclusions can serve the design of LSM propulsion system.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.505-508
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• 2012

A permanent magnet flux switching (PMFS) machine has a simple rotor, whilst both magnets and coils are set in the stator, resulting in easy removal of heat due to both copper loss and eddy current loss in magnets. However, the volume of magnets used in PMFS machines is usually larger than in conventional PM machines, and leakage flux does exist at the non-airgap side. To make full use of the magnets and gain higher power density, a novel 3-dimensional (3D) field PMFS machine is developed. It combines merits of the tubular linear machine, external-rotor rotary machine and axial-flux rotary machine, hence, offers high power density and peak torque capability, as well as efficient utility of magnets owing to the unique configuration of triple airgap fields.

• 전력전자학회논문지
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• 제4권5호
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• pp.474-482
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• 1999

본 논문에서는 유도전동기의 전 속도 영역에서 출력토오크를 최대화 할 수 있는 새로운 약계자 제어기를 제시하였다. 전압제한과 전류제한을 모두 고려한 약계자 영역에서의 최적해를 구하였다. 제안된 알고리즘은 자속과 속도를 근거로 하여 변동하는 전압 제한 조건을 만족시키는 전류 기준값을 구하게 된다. 따라서 고정자 전압을 최대한 활용하므로 정상상태 뿐만 아니라 전동기의 자속의 크기가 변화하는 과도상태에서도 최대 출력 토오크와 빠른제어 응답성을 얻을 수 있다. 시뮬레이션 및 실험결과를 통해 제안된 약계자 기법의 효용성을 보였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.86-88
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• 2008

The rotational loss is one of the most important problems for the practical use of the high power Flywheel Energy Storage System (FESS). This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized any and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the high power FESS.

• 대한전기학회논문지
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• 제40권6호
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• pp.567-573
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• 1991

Full direct digital control of induction motor driver is implemented with a minimal hardware structure. This paper deals with the presentation of a low-cost single-chip microprocessor-based control system for three-phase PWM generation and vector control that control speed of the induction motor using the field-oriented control method. Rotor flux is estimated using the indirect sensing method based on the rotor circuit equation in the synchronously rotation reference frame, and slip angle and rotor position are calculated from rotor angular velocity and stator current. Through simulation and experiment, it is shown that the proposed scheme gives good static and dynamic performance to the induction motor drive.

• 전기학회논문지P
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• 제54권3호
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• pp.134-140
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• 2005

Most of the loads in industrial power distribution systems are usually balanced and connected to three power systems. However, in the user power distribution systems, partial loads are single & three phase and unbalanced, generating voltage unbalance by the impedance mismatching. Voltage unbalance has detrimental effects on three-phase induction motors, including over heating, line-current unbalance, derating, torque pulsation, low efficiency, etc. This paper presents a scheme on operation states of a three-phase induction motor under the unbalanced voltages with harmonics components. Three-phase voltages applied to the stator winding of the studied induction motor are controlled by respectively adjusting not only fundamental but also harmonics components. Harmonic components at the voltage unbalanced factor(VUF) of the three-phase source voltages can then be examined the different values of VUF on machine's operation characteristics.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.125-127
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• 2003

The single phase switched reluctance motor(SRM) is more simpler and robust in the structure than poly phase SRM. It has the merits that it reduces the switching elements and the energy density per volume is very high. Recently, it has been researched and developed in various types and starting method due to the technique of power electronics and the computer added design. The single phase SRM is tried to apply to many industrial appliance field to substitutethe the induction motor by the single phase SRM. On the previous studies, we decided the design parameters of the single phase SRM for the blower driver to adapt the design method of the conventional machine and the poly phase SRM. In this studies, it is proposed the conditions to decide the optimal pole arcs because the stator and rotor pole arcs is very important in the characteristics of the single phase SRM. For this reason, it is analysed the characteristics of current on/off angle vs. pole arc, pole arcs vs. average torque.